This article has described the ZEMAX features which use OpenGL (Shaded Model, NSC Shaded Model and NSC Object Viewer) as well as addressed issues that may arise when using these features. In summary,

• There are a variety of options to use less memory when using OpenGL features in ZEMAX
• Updating the video card driver can solve rendering issues with OpenGL features
• If the video card manufacturer’s driver does not resolve rendering issues, try a Microsoft driver